The present invention relates to an apparatus for image formation on cylindrical surfaces in printing machines comprising multiple processing units arranged side by side and allocated to the plate cylinder of the printing machine. The processing units can be moved axially to the plate cylinder.
A printing machine with a printing unit having a gapless image cylinder,.which is coated with a dryable polymer by a direct image formation process, is known through DE 19612927 A1. The surface characteristic of this polymer layer on the image cylinder is changed completely or partially by a selective laser beam in order to change its affinity to printing ink. The image cylinder is used instead of a plate cylinder in a conventional offset press either in wet offset or dry offset printing. The image cylinder is cleaned from the image carrying layer after finishing printing. The layer must not be removed completely. The radiation source, the coating unit and the drying unit are arranged side by side on a spindle drive and moved by the spindle drive over the width of the cylindrical surface to be imaged. The cleaning unit is mounted separately.
The disadvantage of this solution is the lack of processing space caused by the number and fixed allocation of the processing units. The versatility of this apparatus is insufficient for many applications.
The object of the invention is to provide a compact image formation unit with a broad application range regarding its usage, the sequence in time and variation in time of the process steps.
The present invention accomplishes this by processing units mounted on slides movable separately on a common cross bar. Each slide carries at least one processing unit. The cross bar is located in a gusset area between the plate cylinder and a blanket cylinder.
An advantage of the present invention is the variability of using the process steps. It is also possible to adjust the processing intensity of the processing units according to the process requirements by the time effecting the surface.